Molecular sieve materials, both natural and synthetic, have been demonstrated in the past to be useful as adsorbents and to have catalytic properties for various types of hydrocarbon conversion reactions. Certain molecular sieves, zeolites, AlPOs, mesoporous materials, are ordered, porous crystalline materials having a definite crystalline structure as determined by X-ray diffraction (XRD). Within the crystalline molecular sieve material there are a large number of cavities which may be interconnected by a number of channels or pores. These cavities and pores are uniform in size within a specific molecular sieve material. Because the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as “molecular sieves” and are utilized in a variety of industrial processes.
Such molecular sieves, both natural and synthetic, include a wide variety of positive ion-containing crystalline silicates. These silicates can be described as rigid three-dimensional frameworks of SiO4 and Periodic Table Group 13 element oxide (e.g., AlO4). The tetrahedra are cross-linked by the sharing of oxygen atoms whereby the ratio of the total Group 13 element (e.g., aluminum) and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing the Group 13 element (e.g., aluminum) is balanced by the inclusion in the crystal of a cation, for example a proton, an alkali metal or an alkaline earth metal cation. This can be expressed wherein the ratio of the Group 13 element (e.g., aluminum) to the number of various cations, such as H+, Ca2+/2, Sr2+/2, Na+, K+, or Li+, is equal to unity.
Molecular sieves that find application in catalysis include any of the naturally occurring or synthetic crystalline molecular sieves. Examples of these molecular sieves include large pore zeolites, intermediate pore size zeolites, and small pore zeolites. These zeolites and their isotypes are described in “Atlas of Zeolite Framework Types”, eds. Ch. Baerlocher, L. B. McCusker, D. H. Olson, Elsevier, Sixth Revised Edition, 2007, which is hereby incorporated by reference. A large pore zeolite generally has a pore size of at least about 7  and includes LTL, MAZ, FAU, OFF, *BEA, and MOR framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of large pore zeolites include mazzite, offretite, zeolite L, zeolite Y, zeolite X, omega, and Beta. An intermediate pore size zeolite generally has a pore size from about 5  to less than about 7  and includes, for example, MFI, MEL, EUO, MTT, MFS, AEL, AFO, HEU, FER, MWW, and TON framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of intermediate pore size zeolites include ZSM-5, ZSM-11, ZSM-22, MCM-22, silicalite 1, and silicalite 2. A small pore size zeolite has a pore size from about 3  to less than about 5.0  and includes, for example, CHA, ERI, KFI, LEV and LTA framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of small pore zeolites include ZK-4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, chabazite, zeolite T, and ALPO-17.
SSZ-26 and SSZ-33 are known large pore zeolites which contain a three-dimensional pore system composed of intersecting 10- and 12-ring pores. (See, Lobo et al., “SSZ-26 and SSZ-33: Two Molecular Sieves with Intersecting 10- and 12-Ring Pores” Science, Vol. 262. no. 5139, pp. 1543-1546, Dec. 3, 1993). These two zeolites can be characterized as members of a family of materials in which the two end members are formed by the stacking of layers in an ABAB sequence or an ABCABC sequence. The framework formed by the ABAB stacking sequence (“polymorph A”) is of orthorhombic symmetry and the framework formed by the ABCABC stacking sequence (“polymorph B”) is of monoclinic symmetry. In between these end-member polymorphs there is a whole family of materials that can be characterized by a fault probability “p” of 0%<p<100% (referred to herein as “SSZ-26/33 family”). If the fault probability is p=0%, the end member polymorph B is obtained, and if p=100%, the end member polymorph A is obtained. The aluminosilicate SSZ-26 and the borosilicate SSZ-33 are members of this disordered family of materials and CIT-1 corresponds to a pure or nearly pure polymorph B. (See, CON Framework Datasheet, Baerlocher et al., Atlas of Zeolite Framework Types, 6th Ed. (2007)) (See also, CON powder pattern and SSZ-26/33 family, polymorph A-polymorph B powder pattern simulations of disordered intergrowths, Treacy et al., Collection of Simulated XRD Powder Patterns for Zeolites, 4th Ed., Amsterdam:Elsevier (2001)).
The X-ray diffraction pattern for SSZ-26 can be found in FIG. 1(a) of the present disclosure.
U.S. Pat. No. 7,648,694 describes a process for preparing zeolites of the SSZ-26/33 family using a structure directing agent (SDA) selected from the group consisting of 1,5-bis(N,N-dimethylcyclohexylammonium)pentane dications, 1,4-bis(N-cyclohexylpiperidinium)butane dications and 1,4-bis(N-cyclopentylpiperidinium)butane dications. The entire disclosure of U.S. Pat. No. 7,648,694 is incorporated herein by reference.
According to the present invention, it has now been found that a novel zeolite having an X-ray diffraction pattern which is similar to, but nonetheless distinct from, both the experimental and the simulated patterns of the SSZ-26/33 family of zeolites can be prepared using 1,4-bis(N-isopentylpyrrolidinium)butane dications as the structure directing agent and zeolite Y as an aluminum source. The new zeolite possesses a large micropore volume of 0.24 cc/g, which is higher than the typically measured 0.19-0.21 cc/g for SSZ-26/33 type zeolites.